Modified photo-thermal evaporator and preparation method and application thereof

Abstract

The invention discloses a modified photo-thermal evaporator and a preparation method and application thereof, and belongs to the technical field of solar photo-thermal conversion and advanced manufacturing. A layer of aluminum oxide thin film of a grass-shaped structure is accurately deposited on the surface of the evaporator through an ALD technology, the hydrophilicity, the light absorption rate and the evaporation efficiency of the evaporator are remarkably improved through the thin film, and the service life of the evaporator is prolonged. And the negative influence of salt crystallization on the performance of the evaporator is effectively reduced. The preparation process is simple, low in cost, environment-friendly and pollution-free, large-scale application is expected to be realized, and a brand-new technical path is provided for solving the problem of global water resource shortage.

Description

Technical Field

[0001] The present invention belongs to the field of solar thermal conversion and advanced manufacturing technology, and in particular relates to a modified photothermal evaporator and a preparation method and application thereof. Background Art

[0002] As the global water crisis intensifies, desalination technology, as a key means of alleviating freshwater shortages, is gaining increasing attention. Currently, mainstream desalination technologies include reverse osmosis, multi-stage flash evaporation, and multiple-effect evaporation. While these technologies have met the desalination needs to a certain extent, they still face several challenges. For example, reverse osmosis suffers from high equipment maintenance costs, multi-stage flash evaporation is difficult to scale up, and multiple-effect evaporation has relatively high investment costs.

[0003] In recent years, photothermal evaporators, as an emerging seawater desalination technology, have rapidly attracted widespread attention due to their high efficiency and environmentally friendly characteristics. Photothermal evaporators absorb the energy of sunlight to directly evaporate and condense water into fresh water. They have significant advantages such as not consuming traditional energy, no pollution, and the produced fresh water is of high purity. However, existing photothermal evaporators still face many challenges in practical applications, such as complex manufacturing processes, insufficient material performance, and high costs. These problems seriously limit their large-scale commercial promotion. In addition, existing photothermal evaporators still have problems such as low evaporation efficiency and salt crystallization affecting performance in actual operation. There is an urgent need to develop an innovative solution that is efficient, environmentally friendly and low-cost. Summary of the Invention

[0004] The present invention provides a modified photothermal evaporator, its preparation method and application. Through ALD technology, a grass-like aluminum oxide film is precisely deposited on the surface of the three-dimensional structure evaporator, which not only significantly improves the hydrophilicity, light absorption rate and evaporation efficiency of the evaporator, but also effectively reduces the negative impact of salt crystallization on performance.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions: A method for preparing a modified photothermal evaporator comprises the following steps: preparing a photothermal evaporator as a substrate; Through ALD technology, the number of cycles is precisely controlled to deposit an aluminum oxide film with a thickness of 10-50 nm on the surface of the photothermal evaporator; The ALD-modified samples were treated with hot water immersion to transform the aluminum oxide film into a grass-like structure, thereby obtaining a photothermal evaporator with high anti-reflective properties, excellent hydrophilicity and high specific surface area.

[0006] In the above steps, a three-dimensional photothermal evaporator is selected as the substrate; The parameters for ALD deposition of aluminum oxide are: Reaction chamber temperature: 50~200℃; Reaction source: Trimethylaluminum and water were used to deposit aluminum oxide, and the source temperature was room temperature; Pulse and purge time: The pulses of the metal source and water source are both 1-5 seconds. Each pulse is followed by a 4-20 second purge with high-purity nitrogen to flush away reaction byproducts and residual reaction sources. The parameters for hot water immersion treatment are: Heating temperature: 50~90℃; Heating time: 30~200 min.

[0007] The modified photothermal evaporator is prepared by the above method, and the surface of the photothermal evaporator is modified with an aluminum oxide film having a grass-like structure.

[0008] The modified photothermal evaporator can be used to treat salt water, sewage, and organic dyes.

[0009] Beneficial effects: The present invention provides a modified photothermal evaporator, a preparation method and application thereof, and successfully designs a multifunctional photothermal evaporator modified with aluminum oxide film through the precise surface treatment capability of ALD technology. After the evaporator is treated with ALD coating, the surface morphology is significantly optimized. The grass-like aluminum oxide microstructure not only significantly enhances light absorption and hydrophilicity, but also greatly increases the specific surface area of the evaporator. Compared with the untreated three-dimensional structure evaporator, the evaporator treated by this process has achieved significant improvements in anti-reflective properties, hydrophilicity and specific surface area, thereby having long-term, stable and efficient seawater desalination and sewage treatment capabilities. This method makes full use of the three-dimensional conformality and precise thickness control advantages of ALD technology, ensures the uniformity and functionality of the aluminum oxide film, and provides an innovative and efficient solution for the surface modification of three-dimensional structure evaporators. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 Scanning electron microscope (SEM) images of alumina before and after hot water treatment: (a) alumina film, (b) grass-like alumina.

[0011] Figure 2 Water contact angle images of different evaporator surfaces: (a) pure PLA evaporator, (b) PLA@Al2O3 evaporator, and (c) PLA@G-Al2O3 evaporator.

[0012] Figure 3 Figure 2 is the light absorption rate diagram of PLA evaporator and PLA@G-Al2O3 evaporator in the solar spectrum range.

[0013] Figure 4The water quality change curves of PLA evaporator and PLA@G-Al2O3 evaporator at different heights above the water surface under 1 sun illumination condition.

[0014] Figure 5 Performance of the PLA@G-Al2O3 evaporator operating in 3.5w% brine under 1 sun illumination conditions: (a)-(e) are photos of the evaporator during 24-hour operation, (f) is the corresponding water evaporation curve, and (g) is the water evaporation curve after the evaporator was operated in 3.5% brine for 7 consecutive days, 12 hours per day. DETAILED DESCRIPTION

[0015] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments: Example 1

[0016] A method for preparing a modified photothermal evaporator comprises the following steps: 1) PLA was selected as the raw material, and a fused deposition modeling (FDM) 3D printer was used to prepare a sheet sample with the following parameters: length 10 mm, width 10 mm, and thickness 0.4 mm; 2) The printed sample was heated in 60°C hot water for 60 minutes for hydrophilic treatment. This sample was recorded as PLA. 3) The hydrophilic treated sample was moved into the ALD reaction chamber and 30 nm aluminum oxide (denoted as PLA@Al2O3) was deposited. The parameters for ALD deposition of aluminum oxide are as follows: Reaction chamber temperature: 120 °C; Reaction source: Trimethylaluminum and H2O were used to deposit aluminum oxide, and the source temperature was room temperature; Pulse and purge time: The pulse of the metal source and water source is 2 seconds. Each pulse is followed by an 8-second purge with high-purity nitrogen to flush away reaction byproducts and residual reaction sources. 4) PLA@Al2O3 was immersed in hot water to transform the surface aluminum oxide film into a grass-like aluminum oxide structure (denoted as PLA@G-Al2O3); Figure 1 These are SEM photos before and after hot water treatment. It can be seen that the flat alumina film has transformed into a loose and porous grass-like structure.

[0017] The parameters for the hot water immersion treatment are as follows: Heating temperature: 80 ℃; Heating time: 50 min; 5) The water contact angles of PLA, PLA@Al2O3 and PLA@G-Al2O3 were tested. Figure 2As shown in the figure, the water contact angles of the three are 73.9°, 99.9° and 12.8°, respectively, indicating that the PLA@G-Al2O3 sample has significantly better hydrophilicity than PLA and PLA@Al2O3, providing excellent surface properties for efficient photothermal evaporation. Example 2

[0018] A method for preparing a modified photothermal evaporator comprises the following steps: 1) PLA was selected as the raw material, and the fused deposition modeling (FDM) 3D printing technology was used to prepare a three-dimensional evaporator with a cylindrical grid structure. The specific parameters were: device height 80 mm, radius 10 mm, and grid aperture 0.4 mm.

[0019] 2) The printed device was heated in hot water at 60°C for 60 min to enhance its hydrophilicity. The treated evaporator was recorded as a pure PLA evaporator.

[0020] 3) The hydrophilic PLA evaporator was moved into an atomic layer deposition (ALD) reaction chamber, and a 30 nm thick aluminum oxide film was deposited on the surface and internal grid of the evaporator. The treated evaporator was recorded as PLA@Al2O3 evaporator.

[0021] The parameters for ALD deposition of aluminum oxide are as follows: Reaction chamber temperature: 120 °C; Reaction source: Trimethylaluminum and H2O were used to deposit aluminum oxide, and the source temperature was room temperature; Pulse and purge time: The pulse of the metal source and water source is 2 seconds. Each pulse is followed by an 8-second purge with high-purity nitrogen to flush away reaction byproducts and residual reaction sources. 4) The PLA@Al2O3 evaporator was immersed in hot water to convert the aluminum oxide film on the surface into a grass-like aluminum oxide, and finally a high-efficiency photothermal evaporator was prepared, which was recorded as PLA@G-Al2O3 evaporator.

[0022] The parameters for the hot water immersion treatment are as follows: Heating temperature: 80 ℃; Heating time: 50 min; The light absorption rate of pure PLA evaporator and PLA@G-Al2O3 evaporator was tested, such as Figure 3 As shown in the figure, the light absorption rate of PLA@G-Al2O3 evaporator is significantly higher than that of pure PLA evaporator, indicating that the surface modification significantly improves the light absorption performance.

[0023] Under indoor conditions, a xenon lamp and an AM1.5G filter were used to simulate sunlight to test the water evaporation rate of the evaporator. Figure 4As shown in Figure 2, the evaporation rate of pure PLA evaporator is the highest when it is 50 mm above the water surface, reaching 3.84 kg m -2 h -1 The PLA@G-Al2O3 evaporator has the highest evaporation rate when it is 60 mm above the water surface, reaching 4.97 kg m -2 h -1 Compared with the pure PLA evaporator, the evaporation rate of the PLA@G-Al2O3 evaporator was significantly improved, showing a better photothermal conversion efficiency.

[0024] Use 3.5w% brine to test the salt resistance and stability of the evaporator. Figure 5 (a) - (e) show the salt crystallization on the top surface of the PLA@G-Al2O3 evaporator during the desalination process. The results show that no obvious salt crystals are formed on the top surface of the evaporator, and only a small amount of salt is deposited at the junction of the side and the surface. During the entire desalination process, water can be effectively supplied to the top surface of the evaporator, forming a good salt diffusion channel. The nighttime salt reflux and salt shedding mechanism can effectively remove most of the salt crystals, ensuring the long-term stable operation of the evaporator. The evaporation effect for 24 consecutive hours (12 hours of sunshine plus 12 hours of nighttime) is shown in Figure 2. Figure 5 (f). In addition, Figure 5 (g) shows the evaporation rate curve of the evaporator under 7 consecutive days of 12 hours of sunshine per day. The test results show that the PLA@G-Al2O3 evaporator exhibits excellent stability throughout the entire test period, proving its ability to operate efficiently and long-term, and is suitable for actual seawater desalination and water resource recovery scenarios. Example 3

[0025] A method for preparing a modified photothermal evaporator comprises the following steps: 1) Glucose and zinc microspheres were used as raw materials, and a cylindrical three-dimensional structure evaporator was prepared by zinc-assisted pyrolysis. The specific parameters were: device height 12 cm, radius 9 cm.

[0026] 2) The prepared cylindrical evaporator was moved into the ALD reaction chamber to deposit an aluminum oxide film with a thickness of 10 nm.

[0027] The parameters for ALD deposition of aluminum oxide are as follows: Reaction chamber temperature: 200 °C; Reaction source: Trimethylaluminum and H2O were used to deposit aluminum oxide, and the source temperature was room temperature; Pulse and purge time: The pulse of the metal source and water source is 1 s. Each pulse is followed by a 6 s purge with high-purity nitrogen to flush away reaction byproducts and residual reaction sources. 4) The evaporator on which the aluminum oxide film is deposited is soaked in hot water to form a highly efficient and salt-resistant photothermal evaporator.

[0028] The parameters for the hot water immersion treatment are as follows: Heating temperature: 50 ℃; Heating time: 200 min. Example 4

[0029] A method for preparing a modified photothermal evaporator comprises the following steps: 1) Using acrylonitrile-butadiene-styrene copolymer (ABS) as the raw material, a three-dimensional evaporator with a pyramidal grid structure was fabricated using FDM 3D printing technology. The specific parameters were: the base length and width were both 20 mm, and the height was 30 mm.

[0030] 2) The prepared pyramid-shaped evaporator was moved into the ALD reaction chamber to deposit a 50 nm thick aluminum oxide film. The treated evaporator was designated as ABS@Al2O3 evaporator.

[0031] The parameters for ALD deposition of aluminum oxide are as follows: Reaction chamber temperature: 150 °C; Reaction source: Trimethylaluminum and H2O were used to deposit aluminum oxide, and the source temperature was room temperature; Pulse and purge time: The pulses of the metal source and water source are both 5 s: each pulse is followed by a 20 s purge with high-purity nitrogen to flush away reaction byproducts and residual reaction sources; 3) The ABS@Al2O3 evaporator was immersed in hot water to convert the aluminum oxide film on the surface into a grass-like aluminum oxide, ultimately producing a high-efficiency photothermal evaporator suitable for wastewater treatment, which was recorded as ABS@G-Al2O3 evaporator.

[0032] The parameters for the hot water immersion treatment are as follows: Heating temperature: 90 ℃; Heating time: 30 min. Example 5

[0033] A method for preparing a modified photothermal evaporator comprises the following steps: 1) A natural biomass material, mushroom, was selected and placed in a nitrogen atmosphere and heated at 800°C for 2 hours to complete the carbonization treatment to produce a carbonized mushroom evaporator.

[0034] 2) The carbonized mushroom evaporator was transferred to the ALD reaction chamber and a 40 nm thick aluminum oxide film was deposited to enhance its surface properties.

[0035] The parameters for ALD deposition of aluminum oxide are as follows: Reaction chamber temperature: 150 °C; Reaction source: Trimethylaluminum and H2O were used to deposit aluminum oxide, and the source temperature was room temperature; Pulse and purge time: The pulse duration for both the metal source and the water source is 3 s. Each pulse is followed by a 10 s purge with high-purity nitrogen to flush away reaction byproducts and residual reaction source. 3) The ALD-modified evaporator is immersed in hot water to further optimize its surface structure, enabling it to have efficient photothermal conversion capabilities and excellent sewage treatment performance.

[0036] The parameters for the hot water immersion treatment are as follows: Heating temperature: 70 ℃; Heating time: 150 min.

[0037] The above description is only a preferred embodiment of the present invention. It should be pointed out that those skilled in the art can make corresponding changes and adjustments to the technology of the present invention without departing from the basic principles of the present invention. These changes and adjustments are all within the scope of protection of the present invention.

Claims

1. A method for preparing a modified photothermal evaporator, characterized in that: The following steps are involved: preparing a photothermal evaporator as a substrate; Through ALD technology, the number of cycles is precisely controlled to deposit aluminum oxide thin films on the surface of the photothermal evaporator; The ALD-modified photothermal evaporator was immersed in hot water to transform the aluminum oxide film into a grass-like structure, thereby obtaining a modified photothermal evaporator.

2. The method for preparing a modified photothermal evaporator according to claim 1, characterized in that: The parameters for ALD deposition of aluminum oxide films are: Reaction chamber temperature: 50~200℃; Reaction source: trimethylaluminum and water, the source temperature is room temperature; Pulse time: The pulse time of metal source and water source is 1~5 s.

3. The method for preparing a modified photothermal evaporator according to claim 1 or 2, characterized in that: During the ALD deposition process, each pulse is followed by a 4-20 s purge with high-purity nitrogen to flush away reaction byproducts and residual reaction sources.

4. The method for preparing a modified photothermal evaporator according to claim 1, wherein: Aluminum oxide films with a thickness of 10~50 nm were deposited on the surface of a photothermal evaporator by ALD.

5. The method for preparing a modified photothermal evaporator according to claim 1, characterized in that: The temperature of hot water immersion treatment is 50~90℃.

6. The method for preparing a modified photothermal evaporator according to claim 1 or 5, characterized in that: The hot water immersion treatment time is 30~200 min.

7. The method for preparing a modified photothermal evaporator according to claim 1, characterized in that: The photothermal evaporator has a three-dimensional structure or a sheet structure.

8. A modified photothermal evaporator, characterized in that: The surface of the photothermal evaporator is modified with grass-like structure aluminum oxide.

9. The use of the modified photothermal evaporator according to claim 8, characterized in that: The modified photothermal evaporator is used for seawater desalination.

10. The use of the modified photothermal evaporator according to claim 8, characterized in that: The modified photothermal evaporator is used for treating sewage or organic dyes.

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